The present invention relates to a power driver for threaded fasteners, such as screws, nuts and the like.
Power drivers of this type are manually-held units reserved to tighten and loosen screws, nuts and the like. They are known for applications where relatively low torque is required, and because of this, these prior-art drivers do not have any arrangements for disconnecting the drive motor from the output shaft or spindle when a maximum permissible torque is reached which acts upon the output spindle, i.e., when the fastener has been threaded tight to the maximum extent. Instead, it is sufficient to interrupt the supply of energy to the motor when the maximum permissible torque is reached. This type of power driver is, for instance, disclosed in U.S. Pat. Nos. 2,964,151 and 2,986,052 in which the motor is an air motor.
In many instances, power drivers of this prior-art type cannot be used, or can be used only with difficulty, because they are of necessity relatively long due to the fact that the air motor, the step-down gear and other components must be arranged in line. They can, therefore, not be used in applications where there is relatively little space.